List Merge(List L1, List L2)
{
 List L,p,q,r;
 L= (List)malloc(sizeof(List));
 p = L1->Next;
 q = L2->Next;
 r = L;
 while (p != NULL && q != NULL)
 {
  if (p->Data < q->Data)
  {
   r->Next = p;
   r = p;
   p = p->Next;
  }
  else 
  {
   r->Next = q;
   r = q;
   q = q->Next;
  }
 }
 r->Next = p ? p : q;
 L1->Next = NULL;
 L2->Next = NULL;
 return L;
}